Arsenate removal from aqueous solutions using micellar-enhanced ultrafiltration

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Arsenate (As-V) contamination in water poses significant health risks.
• Conventional water treatment methods can be inefficient for arsenic removal.
• Micellar enhanced ultrafiltration (MEUF) offers a promising alternative for contaminant removal.

Purpose of the Study:

• To investigate the efficacy of micellar enhanced ultrafiltration (MEUF) for arsenate (As-V) removal.
• To evaluate the performance of polyacrylonitrile (PAN) membranes modified with cationic surfactants for As-V removal.
• To study the influence of various operating parameters on MEUF performance for arsenic remediation.

Main Methods:

• Fabrication of polyacrylonitrile (PAN) ultrafiltration (UF) membranes via phase inversion.
• Characterization of membrane morphology and properties.
• Experimental investigation of MEUF using cationic surfactants (CPC and HTAB) in a dead-end filtration system.
• Analysis of As-V removal, surfactant rejection, and permeate flux under varying conditions (As-V concentration, surfactant type, pH, membrane thickness, co-existing anions).

Main Results:

• Cetyl-pyridinium chloride (CPC) showed higher As-V removal efficiency (91.7%) compared to hexadecyltrimethyl-ammonium bromide (HTAB) (83.7%).
• Optimal As-V removal of 100% was achieved at pH 7, with initial As-V concentrations of 100-1000 μg/L, and a membrane thickness of 150 μm.
• The PAN membrane selectively removed arsenic and anions from well water without significantly affecting cations, outperforming Reverse Osmosis (RO) and Nanofiltration (NF) in selectivity.

Conclusions:

• MEUF with cationic surfactants, particularly CPC, is highly effective for arsenate removal using PAN membranes.
• The dead-end filtration system demonstrated comparable arsenic removal efficiency to cross-flow systems with reduced flux reduction.
• The developed PAN-based MEUF process offers a selective and efficient method for arsenic remediation in drinking water.